JPH04124267A - Ion implanting device - Google Patents

Abstract

PURPOSE:To neutralize the positive charges on a semiconductor wafer without generating dielectric breakdown by analyzing only the electrons of low energy among the electrons generated from an electron generator and supplying these electrons to the semiconductor wafer. CONSTITUTION:The positive ions of <75>As<+> formed in an arc chamber are drawn out by a drawing out electrode and the surface of the wafer 9 is irradiated and implanted with these ions. Thermions are formed by passing a current to the filament 110 of the electron generator 100 of the above-mentioned ion implantation device and are drawn out by the drawing out electrode 150. The thermions are applied to an energy analyzer 140. The thermions of the energy larger than a set value are removed by passing an orbit (a) and the thermions of the energy smaller than the set value by passing an orbit (c). The thermions having the same energy as the set value pass an orbit (b) and the slit 160 and the surface of the wafer 9 is irradiated with these thermions. Only the thermions of the low energy are thereby supplied to the wafer 9 to neutralize the positive charge on the wafer 9 and, therefore, the generation of the dielectric breakdown is obviated.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an ion implantation device equipped with an electron neutralizer for neutralizing the positive charge of a semiconductor wafer when positive ions are implanted into the semiconductor wafer. .

[Conventional technology]

FIG. 2 is a schematic diagram of a general large current ion implantation device. In the figure, 1 is an arc chamber which is an ion source; 2 is a filament installed in the actuator no. 1 for emitting thermoelectrons; 3 is an extraction electrode 5 for extracting ions generated within the arc chamber; A mass analyzer 5 extracts ions of a predetermined mass from among the ions extracted by the extraction electrode 3, and 5 is used to extract ions having a predetermined mass from among the ions extracted by the mass analyzer 4. 6 is a shaping slit for limiting the beam area, 7 is a Faraday beam amount measurement system, and 8 is a disk on which the wafer 9 is placed.

Next, the operation will be explained. A gas (A s
Hs, etc.). When a current is passed through filament 2,
Thermionic electrons are emitted from the filament 2 and collide with the gas, so that the inside of the arc chamber 1 becomes a plasma state, and ions such as 75As"As"As+ are generated. These ions are extracted from a beam extraction slit (not shown) in the arc chamber 1 by applying a negative bias to the extraction electrode 3.

Since the extracted ion beam contains duplicate isotopes such as As and As2'' and different types of ions, a mass spectrometer 4 is used to extract the necessary 75As+ from among them.This mass The analyzer 4 selects the ion mass by changing the magnetic field.In other words, ions with a heavy mass due to 75As+ ions collide into the analysis tube without being able to bend through the tube, while ions with a light mass bend in the opposite direction. It will easily collide into the analysis tube in the same way. The ion beam mainly containing 75AS" extracted in this way is passed through the analysis slit 5 to remove ions with a mass close to 75As1, and the shaping slit 6 further reduces the beam area. is limited. Then, the ion beam passes through a Faraday 7, which is a beam amount measuring system, and is implanted onto the surface of a wafer 9 loaded on a disk 8. The Faraday 7 is equipped with an electron neutralizer as shown in FIG. 3 to prevent positive charging on the surface of the wafer 9 during ion implantation.

FIG. 3 is a schematic diagram of a conventional electron neutralizer installed in an ion implanter. Electron neutralizer is electron generator 10
0 and filament 110. Thermal electrons generated by passing a current through the filament 110 of the electron generator 100 during ion implantation are extracted from a slit provided on the Faraday cup 130 by an electric field generated by positively biasing the Faraday cup 30.

These thermionic electrons are transferred to the Faraday cup 1 facing the electron neutralizer.
30 and induces electrons of various energies, such as recoil electrons and secondary electrons. By irradiating the surface of the wafer 9 with these electrons, the surface of the wafer 9 is prevented from being positively charged by positive ions during ion implantation.

[Invention or problem to be solved]

In the electron neutralizer of the conventional large current ion implantation apparatus, thermionic electrons generated by the electron generator 100 collide with the Faraday cup 130, and recoil electrons and secondary electrons generated are supplied to the surface of the wafer 9, and the wafer It neutralizes the positive charge of 9. Some of these electrons have high energy and some have low energy. High energy electrons are on wafer 9
There was a problem in that the surface of the capacitor was negatively charged, causing dielectric breakdown in devices such as capacitor structures.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to obtain an ion implantation apparatus having an electron neutralizer that can supply only low-energy electrons to the wafer surface.

[Means to solve the problem]

The present invention is applied to an ion implantation apparatus equipped with an electron neutralizer for neutralizing the positive charge of a semiconductor wafer when positive ions are implanted into the semiconductor wafer.

The ion implantation apparatus according to the present invention is an electron neutralizer comprising an electron generator and an energy analyzer that selects only electrons having a predetermined energy from among the electrons generated from the electron generator and supplies them to the semiconductor wafer. It is characterized by having a container.

[Effect]

The electron neutralizer in this invention is equipped with an energy analyzer that selects only electrons having a predetermined energy from among the electrons generated from the electron generator and supplies them to the semiconductor wafer. Of these, only low-energy electrons can be supplied to the semiconductor wafer.

〔Example〕

FIG. 1 is a schematic diagram of an electron neutralizer used in an ion implantation apparatus according to the present invention. In the figure, the difference from the conventional electron neutralizer shown in FIG. 3 is that an energy analyzer 140 is newly provided. The energy analyzer 140 selects only electrons with a predetermined energy from among the electrons from the electron generator 100 and supplies them to the wafer 9. The rest of the structure is similar to the conventional electron neutralizer shown in FIG.

Next, the operation will be explained. Positive ions such as 75As+ generated in the arc chamber are extracted by an extraction electrode, and then passed through the mass spectrometer, analysis slit, and molded sleeve I.
, passes through Faraday and is irradiated onto the surface of the wafer 9, as in the conventional case.

The electron neutralizer will be explained below. When a current is passed through the filament 110 of the electron generator 100, thermoelectrons are generated. When a positive bias is applied to the extraction electrode 150, an electric field is generated, and thermoelectrons are extracted by this electric field. These thermoelectrons include a plurality of electrons having different energies. These thermoelectrons are provided to an energy analyzer 140. Among the thermoelectrons that have entered the energy analyzer 140, those with energy greater than the set value of the energy analyzer 140 pass through the a orbit, and those with lower energy pass through the C orbit and are removed. Thermionic electrons having the same energy as the set value (for example, 10 eV) pass through the orbit b, pass through the slit 160, and are irradiated onto the surface of the wafer 9.

As described above, in this embodiment, the energy analyzer 14
0 and supplying only low-energy (10 eV) thermoelectrons to the wafer 9, the positive charge on the wafer 9 that causes positive charging is neutralized, so there is no dielectric breakdown as in the conventional case. It will never occur.

〔Effect of the invention〕

As described above, according to the present invention, an electron neutralizer includes an electron generator and an energy analyzer that selects only electrons having a predetermined energy from among the electrons generated from the electron generator and supplies the selected electrons to the semiconductor Uninow. As a result, only low-energy electrons generated from the electron generator can be supplied to the semiconductor wafer, and as a result, positive charges on the semiconductor wafer 1 can be neutralized without causing dielectric breakdown. It has the effect of being able to harmonize.

[Brief explanation of the drawing]

Figure 1 is a schematic configuration diagram of an electron neutralizer used in the ion implantation apparatus according to the present invention, Figure 2 is a configuration diagram of a conventional general high-current ion implantation apparatus, and Figure 3 is a conventional electron neutralizer. FIG. In the figure, 9 is a wafer, 100 is an electron generator, 140
is an energy analyzer. Note that the same reference numerals in each figure indicate the same or corresponding parts. Procedural amendment (voluntary)

Claims (1)

[Claims] (1) In an ion implantation apparatus equipped with an electron neutralizer for neutralizing the positive charge of the semiconductor wafer when positive ions are implanted into the semiconductor wafer, the electron neutralizer includes: an electron generator; and the electron An ion implantation apparatus comprising an energy analyzer that selects only electrons having a predetermined energy from among electrons generated from a generator and supplies the selected electrons to the semiconductor wafer.